A method for simultaneous determination of trace of four organophosphorus pesticides residues in animal liver samples has been developed and validated. This method is based on the preliminary sample preparation using extraction of target compound with a mixture of toluene-cyclohexane by means of up-to-date accelerated solvent extraction (ASE), liquid-liquid partitioning with acetonitrile and hexane, additional clean up step using QuEChERS method. Further the obtained analytes are determined by gas chromatography with ion-trap detector. The validation of the method is performed in accordance with the recommendations in Document SANTE/11945/2015 and it meets the acceptability criteria for precision, mean recovery and limits of quantification. The samples were investigated by analysing blank liver samples and samples spiked with the target analytes chlorpyrifos-methyl, parathion and pirimiphos-methyl at levels of 25, 50, and 75 ng/g and with diazinon at levels of 15, 30, and 45 ng/g. The recovery for all compounds were in the range from 73 to 104% which perfectly fit with requirements of documents and European legislations. The repeatability and within-laboratory reproducibility also reveal acceptable in documents coefficient of variation and uncertainty less than 20 and 18%, respectively. The limits of quantification were less than 3 ng/g for all compounds and allowed determination of residues below the maximum residue levels (MRLs) set in Regulation (EC) Nº 396/2005.
The authorities have identified an emerging trend where over-the-counter products, represented as dietary supplements, contain hidden active ingredients that could be harmful. Consumers may unknowingly take products laced with varying quantities of approved prescription drug ingredients, controlled substances, and untested and unstudied pharmaceutically active ingredients. Hidden ingredients are increasingly becoming a problem in products promoted for sexual enhancement, weight loss, or bodybuilding. The tests have revealed the presence of some undesired substances like sildenafil, tadalafil, vardenafil, and their analogues in tainted sexual enhancement products. The content of these substances is usually around the daily curative dose. A simple high-performance liquid chromatography (HPLC) method for simultaneously determination of sildenafil, vardenafil, tadalafil, dapoxetine, yohimbine, and sibutramine was developed and validated. InfinityLab Poroshell 120 EC-C18 (150 '4.6 mm '4 μm particles) was used, as well as a diode-array detector (DAD) at 230 nm, and a gradient flow with 0.030 М ammonium acetate buffer and acetonitrile. The method is linear in the following range: 2.5–37.5 μg/mL for yohimbine, 2.06–30.9 μg/mL for vardenafil, 2.0–30.0 μg/mL for sildenafil, 3.1–46.5 μg/mL for tadalafil, 1.98–29.7 μg/mL for dapoxetine, and 2.2–66.0 μg/mL for sibutramine. The linearity coefficient is R2 = 1 for all substances. Model matrices were spiked, and the analytical recoveries for all substances are in the range 97.5%–99.5%. The method exhibited an upper hand compared with previously reported methods in terms of speed and simplicity. Additionally, the mobile phase (also used as extracting, column washing, and diluting solvent) was composed of only buffer and acetonitrile, which rendered the method much cheaper than others.
The major processes for introducing polycyclic aromatic hydrocarbons (PAHs) in food are smoking and grilling of different products. But in addition, PAHs can permeate in the food chain due to their high lipophilicity and ability to be accumulated in specific tissue, through contaminated animal feed. Further, when some parts of these animals are marketed as food, the accumulated PAHs can go to the human organism. Some of them are classified as highly toxic, carcinogenic and mutagenic for animal and human organisms so they are under consideration of International and European legislation. This work reports development and validation of simple and fast GC/MS method for 16 PAHs determination. Comparison of two methods for sample preparation in pork meat matrix standard extraction/saponification procedure and modified QuEChERS method is also done. In addition, this paper report the calibration step of instrument and a recovery study for 16 PAHs in model pork meat, using modified QuEChERS procedure for sample pretreatment. The calibration step with accessible and suitable for use in real laboratory conditions internal standard (chrysene D12) is done in the range 10–100 ppb using toluene as solvent. The obtained results show very good linearity (R2 = 0.99 to 1.00). For the recovery study six model samples were spiked with 16 PAHs and they all are subjected to QuEChERS procedure. The recovery is calculated and the obtained data (71–120%) is in a good correlation with requirements of international legislation. Finally, LOD values for all 16 investigated compounds of modified GC/MS method and for the instrument were determined.